A transportation refrigeration system includes a compartment to be conditioned. A refrigeration circuit is associated with an enclosure including a compressor. A condenser and an expansion valve are upstream of a first evaporator and a second evaporator. The first evaporator is in parallel with the second evaporator. A first enclosure surrounds the first evaporator. The first enclosure includes a first refrigerant detection sensor in communication with a controller. A second enclosure surrounds the second evaporator. The second enclosure includes a second refrigeration detection sensor in communication with the controller.

A load balancing method for two compressors. The two compressors are used in a refrigeration system and are driven coaxially by the same driving device. The method comprises the steps of obtaining parameters, determining balance, and controlling start/stop states. The parameters in the step of obtaining parameters are parameters related to the two compressors, such as a compressor suction side flow rate, or exhaust side flow rate, or suction side temperature; the step of determining balance comprises determining, on the basis of the obtained parameters related to the two compressors, whether load is balanced between the two compressors; the step of controlling start/top states comprises controlling the start/stop states of the two compressors according to whether the load is balanced. The method can monitor the load balance state of two compressors that are coaxially driven, thereby effectively avoiding failure of the refrigeration system caused by unbalanced loads of the compressors.

A compressor system includes a first compressor and a second compressor. A suction equalization line fluidly couples the first compressor and the second compressor. A first branch suction line is fluidly coupled to the first compressor and a second branch suction line is fluidly coupled to the second compressor. A main suction line is fluidly coupled to the first branch suction line and the second branch suction line. An obstruction device is disposed in at least one of the first branch suction line and the second branch suction line. Responsive to deactivation of at least one of the first compressor and the second compressor, the obstruction device is at least partially closed thereby causing prescribed liquid levels in the first compressor and the second compressor during partial-load operation.

A refrigerant circuit has a liquid passage that allows a receiver to communicate with a utilization heat exchanger, and a first expansion valve provided in the liquid passage. The controller opens the first expansion valve when the compression element is in the stopped state and a pressure in the receiver exceeds a predetermined first pressure.

A control method for a heat pump unit includes acquiring a first output capability set when the heat pump unit reaches a first preset energy efficiency ratio set at a current ambient temperature; acquiring a total demand load demanded by an indoor area having a heating demand or a cooling demand; and causing the heat pump unit to operate in accordance with the first output capability set when the total demand load is smaller than the first output capability set.

A method of operating a refrigeration system includes initiating a compressor shutdown operation, determining a difference in a saturation temperature at a port of a compressor of the refrigeration system and an ambient temperature and comparing the difference in the saturation temperature and ambient temperature with a threshold. If the difference in the saturation temperature and ambient temperature is less than or equal to the threshold, a pump down operation is performed and if the difference in the saturation temperature and ambient temperature exceeds the threshold, a compressor shutdown operation is completed.

A fluid control assembly is provided, which includes a heat exchange core, a mounting block and a valve core member. At least a part of the valve core member is arranged in a first mounting hole passage of the mounting block, and the valve core member is sealable to a wall portion of the first mounting hole passage. In this way, the fluid control assembly includes a fluid flow passage that includes a first port, a second hole passage, a first hole passage, a first sub-passage, a communication hole, a second sub-passage, and a second port. A core body of the valve core member is operated under a pressure difference between the first sub-passage and the second sub-passage, to communicate or block the first sub-passage and the second sub-passage, to realize a constant flow direction of the fluid flow passage of the fluid control assembly.

In a method for operating a compressor (22) having an inlet (26) and an outlet (28), the method includes: running the compressor to compress a fluid; shutting down (422) the compressor; determining (420) a condition-dependent threshold restart pressure difference (threshold) across the compressor; relieving the pressure difference to reach the threshold; and, after the threshold is reached, restarting (434) the compressor.

A method of monitoring an air cycle machine including driving a rotary shaft of an air cycle machine, disconnecting a driving source to allow the rotary shaft to slow the rotary shaft, and monitoring a shutdown cycle of the rotary shaft.

A system includes a heat-pump circuit and a heating-fluid circuit. The heat-pump circuit includes a compressor and a first condenser conduit. The heating-fluid circuit includes first, second, and third flow-paths. The third flow-path selectively communicates with the first and second flow-paths. The first flow-path includes a first valve. The first valve moves between an open position allowing fluid flow through the first flow-path and a closed position restricting fluid flow through the first flow-path. The second flow-path includes a second condenser conduit and a second valve. When the second valve is open, fluid flows through the second flow-path. In the closed position, the second valve restricts fluid flow through the second flow-path. The third flow-path includes a heat exchanger receiving fluid from the first flow-path when the first valve is in the open position and receiving fluid from the second flow-path when the second valve is in the open position.